“Qi” wireless power standard promises cord-free charging

Mobile devices will soon be able to add wireless charging as a standard …

A universal standard for charging devices wirelessly is close to becoming a reality, as the Wireless Power Consortium finalized the interface definition for a low-power specification this past Friday. That interface definition is already available internally and will be published publicly on August 30, though WPC said that performance requirements and compliance testing documents will only be available to consortium members.

The current spec maxes out at 5 Watts of power. That should be sufficient for most common mobile devices, many of which already charge via USB ports that max out at 2.5W (5V at 500mA). The spec is open enough to allow a wide variety of design solutions, such as a magnetically aligned coil that is used for the Palm Pre's Touchstone charger, or an array of coils activated individually depending on device placement.

In addition to the standard, however, WPC has a series of tests for specification compliance. Devices purporting to comply with the standard will have to pass third-party certification before the manufacturer is allowed to use the trademarked "Qi" logo on the device or its packaging. This is designed to make it easy for consumers to find interoperable chargers and devices.

"Our customers will see the Qi logo and know: this product works with my other Qi products," wrote Menno Treffers, a senior director of standardization at Philips who works with the consortium. "Publishing a standard is not enough. Without test documentation, certification services, and a logo license agreement, interoperability is an illusion."

If I understand correctly, this is more like the charger for electric toothbrushes rather than long distance wireless chargers. The idea is for a "charging pad" where you can put any compatible devices on it to charge the device so you don't have to find the right connector to connect the devices.

How much wasted power is there compared to a wired solution? If there is nothing to charge, does it still draw power?

It should be pretty much the same. With a 'wall wart' charger, the whole transformer is in the charger (assuming it has a transformer). While the primary winding is energized, there are some small losses such as eddy currents (small currents induced into the transformer core), but no power is lost until a 'load' is put on the secondary winding that it's magnetically coupled to. The difference with these devices is that the secondary winding is in the device, not in the charger. So without the device on the charger, you have no load, just like having an unplugged wall wart.

If I understand correctly, this is more like the charger for electric toothbrushes rather than long distance wireless chargers. The idea is for a "charging pad" where you can put any compatible devices on it to charge the device so you don't have to find the right connector to connect the devices.

That could still be quite useful though for certain applications in that it allows increased ruggedness. For some devices the charging port or area is the only semi-exposed or more moisture sensitive area left. Freeing devices from requiring any ports whatsoever, anywhere (Cell/WiFi/Bluetooth for data links, now standardized wireless power) could enable some nice new designs.

"Our customers will see the Qi logo and know: this product works with my other Qi products," wrote Menno Treffers, a senior director of standardization at Philips who works with the consortium. "Publishing a standard is not enough. Without test documentation, certification services, and a logo license agreement, interoperability is an illusion."

Glad to see someone in the industry really gets it! I'm so sick of having separate, special chargers for everything.

xoa wrote:

That could still be quite useful though for certain applications in that it allows increased ruggedness. For some devices the charging port or area is the only semi-exposed or more moisture sensitive area left. Freeing devices from requiring any ports whatsoever, anywhere (Cell/WiFi/Bluetooth for data links, now standardized wireless power) could enable some nice new designs.

I read about a standard earlier that could run a toaster - if we could at least get kits to retrofit existing furniture or surfaces that would be boss. I'd wire my tables, couches, tables and counters.

I can't get excited about this because if I have to put my phone on a mat then it's not much more difficult to stick it in a dock. The benefits don't seem to outweigh the power costs.

A universal charging standard would be great, but there is no technical reason why that can't exist with wired chargers. If this technology takes off I imagine we'll see a proliferation of incompatible standards. Why adopt the open standard when you can sell your own chargers at a special price?

Awesome! I have a sort of OCD toward wires and trying to go as wireless as possible… I still use a wire mouse for gaming but everything else is Bluetooth (keyboard, headphones, etc)… I would actually be looking forward to wireless speakers as well… 5w is fine for a small 2.0 set and the audio can be sent via Bluetooth or standard 2.4ghz

How much wasted power is there compared to a wired solution? If there is nothing to charge, does it still draw power?

It should be pretty much the same. With a 'wall wart' charger, the whole transformer is in the charger (assuming it has a transformer). While the primary winding is energized, there are some small losses such as eddy currents (small currents induced into the transformer core), but no power is lost until a 'load' is put on the secondary winding that it's magnetically coupled to. The difference with these devices is that the secondary winding is in the device, not in the charger. So without the device on the charger, you have no load, just like having an unplugged wall wart.

In California transformer based 'wall-warts' are no longer legal because of the losses that exist when they're not charging anything. There's actually a bit of power lost when no load is connected to a transformer based wall-wart (touch one when it's not charging anything and it still feels warm, that's power being wasted). When you take into account the millions of wall-warts plugged in 24/7 it starts to add up. All new devices must use switching power supplies, which are more efficient, don't use transformers, and use very little power when not charging a device (some companies even claim "Zero Power"). We've have to change over to switching power supplies on all the products we sell that use wall-warts. (That and because of the law change, it's become hard to find large quantities of transformer based supplies.)

My guess is even though a switching power supply is more efficient while charging, than a Qi supply will be, it wouldn't be hard to design a Qi power supplied that turned itself off, when the device it was charging was not present, so in the long run, the amount of power wasted by either would be similar. It wouldn't surprise me to see this as part of the spec. As long as there is no (or very little power wasted) when not charging, California (and possibly other states) will be happy.

Of course you will be able to. You'll see iPhone/Android Phone cases with the hardware built into them in no time, once products start hitting the market.

I'm betting their single-biggest item the first year it's out is after-market case/chargers.

They already exist. There is a system called PowerMat that works this way (though I don't know if it is Qi compliant). It's been available for over a year.

Yeah, this.

I'm not sure what the drool-factor is about. Duracell also has a charge pad out that you can buy now.

The main drawback seems to be the cases that everyone seems to be looking forward to ( ) - because they add bulk.

I won't mind it when the system is built into new devices and doesn't add bulk to it, because I really hate having to buy all new chargers every 2 years because the industry moves from mini to micro to who knows what next. Also, it will be neat when auto makers begin integrating charging mats into the consoles of cars, thus eliminating the need for all those annoying car chargers.

Apple may very well continue to create their own proprietary chargers, and keep the 3rd party market for them alive, due to profit margins on add-ons. A single universal charging mat would destroy entire product lines and, perhaps, entire small businesses. Doesn't make it bad, just stating the obvious from a business-decision angle.

I think I might convert over to a wireless mouse if it charges from the mousepad.

These have actually existed for years. The problem is it locks you to a specific mouse and pad, both of which people can be picking about (I prefer a large mouse and a large mouse pad). There is also the issue that the mouse won't work anywhere off of the pad, which is occasionally needed.

Of course if there were a whole slew of Qi compatible mice, and a bunch of Qi compatible mouse pads, the story might be different.

Awesome! I have a sort of OCD toward wires and trying to go as wireless as possible… I still use a wire mouse for gaming but everything else is Bluetooth (keyboard, headphones, etc)… I would actually be looking forward to wireless speakers as well… 5w is fine for a small 2.0 set and the audio can be sent via Bluetooth or standard 2.4ghz

This is a standard for contact/near contact charging. You'd just be swapping a power wire from the speakers for a power wire to the charging mat directly under the speakers. I fail to see how this would be an improvement.

Awesome! I have a sort of OCD toward wires and trying to go as wireless as possible… I still use a wire mouse for gaming but everything else is Bluetooth (keyboard, headphones, etc)… I would actually be looking forward to wireless speakers as well… 5w is fine for a small 2.0 set and the audio can be sent via Bluetooth or standard 2.4ghz

This is a standard for contact/near contact charging. You'd just be swapping a power wire from the speakers for a power wire to the charging mat directly under the speakers. I fail to see how this would be an improvement.

Yeah, but if Norazi gets a large (zoned, maybe, to allow multiple devices totaling more than 5W?) charging mat that covers the entire desk surface, it will only take 1 power wire for everything.

Apple may very well continue to create their own proprietary chargers, and keep the 3rd party market for them alive, due to profit margins on add-ons. A single universal charging mat would destroy entire product lines and, perhaps, entire small businesses. Doesn't make it bad, just stating the obvious from a business-decision angle.

It'll happen because preserving outdated business models is an American tradition (HELLOOOOOO RIAA and Detroit!)

Now I"m even more amused. Either the artist knew what he was doing and is a total genius, or the similarity will be lost on enough people that it'll become entrenched and used everywhere before (enough people) notice.